#include<stdio.h>
#include<math.h>
int main()
{
	int n, i, k;
	printf("please enter an interge number:n = ?");
	scanf_s("%d", &n);
	k = sqrt(n);
	for (i = 2;i <= k;i++)
		if (n % i == 0)break;
	if (i <= k)printf("%d is not a prime number.\n", n);
	else printf("%d is a prime number.\n", n);
	return 0;
}